The relationship between upper-ocean variability and the Madden-Julian Oscillation in extended-range simulations

2015 ◽  
Author(s):  
Xiaodong Hong ◽  
Carolyn A. Reynolds ◽  
James D. Doyle ◽  
Paul May
Keyword(s):  
Upper Ocean ◽  
Madden Julian Oscillation ◽  
Ocean Variability ◽  
Extended Range ◽  
The Relationship

Surface Wind and Upper-Ocean Variability Associated with the Madden–Julian Oscillation Simulated by the Coupled Ocean–Atmosphere Mesoscale Prediction System (COAMPS)

2013 ◽  
Vol 141 (7) ◽  
pp. 2290-2307 ◽  
Author(s):  
Toshiaki Shinoda ◽  
Tommy G. Jensen ◽  
Maria Flatau ◽  
Sue Chen
Keyword(s):  
High Resolution ◽  
Indian Ocean ◽  
Surface Wind ◽  
Upper Ocean ◽  
Prediction System ◽  
Madden Julian Oscillation ◽  
Atmospheric Component ◽  
Ocean Variability ◽  
Ocean Atmosphere ◽  
Nested Grid

Abstract Simulation of surface wind and upper-ocean variability associated with the Madden–Julian oscillation (MJO) by a regional coupled model, the Coupled Ocean–Atmosphere Mesoscale Prediction System (COAMPS), is evaluated by the comparison with in situ and satellite observations. COAMPS is configured for the tropical Indian Ocean domain with the horizontal resolution of 27 km for the atmospheric component and ⅛° for the ocean component. A high-resolution nested grid (9 km) for the atmospheric component is used for the central Indian Ocean. While observational data are assimilated into the atmospheric component, no data are assimilated into the ocean component. The model was integrated during 1 March–30 April 2009 when an active episode of large-scale convection associated with the MJO passed eastward across the Indian Ocean. During this MJO event, strong surface westerly winds (~8 m s−1) were observed in the central equatorial Indian Ocean, and they generated a strong eastward jet (~1 m s−1) on the equator. COAMPS can realistically simulate these surface wind and upper-ocean variations. The sensitivity of upper-ocean variability to the atmospheric model resolution is examined by the COAMPS experiment without the high-resolution nested grid. The equatorial jet generated in this experiment is about 20% weaker than that in the first experiment, which significantly influences upper-ocean salinity and temperature. The large diurnal warming of SST during the suppressed phase of the MJO is also adequately simulated by the model. Weak winds during this period are mostly responsible for the large SST diurnal variation based on the comparison with the spatial variation of surface forcing fields.

A Statistical Extended-Range Tropical Forecast Model Based on the Slow Evolution of the Madden–Julian Oscillation

1999 ◽  
Vol 12 (7) ◽  
pp. 1918-1939 ◽  
Author(s):  
Duane E. Waliser ◽  
Charles Jones ◽  
Jae-Kyung E. Schemm ◽  
Nicholas E. Graham
Keyword(s):  
Forecast Model ◽  
Madden Julian Oscillation ◽  
Model Based ◽  
Extended Range ◽  
Slow Evolution

scholarly journals UPPER OCEAN VARIABILITY IN THE BAY OF BENGAL DURING 2006 IOD

2009 ◽  
pp. 197-211
Author(s):  
P. SWAPNA ◽  
N. BAHULAYAN ◽  
N. A. DIANSKY
Keyword(s):  
Bay Of Bengal ◽  
Upper Ocean ◽  
Ocean Variability

scholarly journals Assessing the Relationship between MJO and Equatorial Pacific WWBs in Observations and CMIP5 Models

2018 ◽  
Vol 31 (16) ◽  
pp. 6393-6410 ◽  
Author(s):  
Jie Feng ◽  
Tao Lian
Keyword(s):  
Temperature Anomaly ◽  
Equatorial Pacific ◽  
Cmip5 Models ◽  
Madden Julian Oscillation ◽  
Sea Surface Temperature Anomaly ◽  
Anomalous Surface ◽  
Favorable Conditions ◽  
The Relationship ◽  
Wind Bursts ◽  
The Tropical Pacific

This study evaluates the relationship between the Madden–Julian oscillation (MJO) and the occurrence of equatorial Pacific westerly wind bursts (WWBs). During the convective MJO phase, anomalous surface westerlies prevail in and west of the convective MJO center, providing favorable conditions for WWBs. Compared with the probability of WWBs expected under a null hypothesis that WWBs occur randomly, the convective MJO phase almost doubles the probability of a WWB occurring. Nevertheless, only 34.46% of WWBs co-occur with the convective MJO, which is much less than that reported in previous studies. We show that when the MJO and WWBs are defined using the same field with overlapping frequencies, the percentage of WWBs co-occurring with the convective MJO shows a significant increase. However, the higher percentage is simply caused by the fact that the strong WWBs during a convective MJO are more likely to be identified than those during the suppressed and neutral MJO phases. A total of 45.80% of WWBs are found to occur in the full MJO phase (both the convective and suppressed MJO phases), which is slightly higher than that expected based on randomness. Although the full MJO has statistically significant impact on the likelihood of WWBs, the influence from the full MJO on the tropical Pacific sea surface temperature anomaly is much weaker as compared to that from the WWBs. The relationships between the MJO and WWBs simulated in CMIP5 models are also assessed, and the percentage of WWBs that co-occur with the MJO simulated in models is in general less than that in observations.

Removing vibrator‐induced correlation artifacts by filtering in frequency‐uncorrelated time space

Geophysics ◽  
1992 ◽  
Vol 57 (7) ◽  
pp. 916-926 ◽  
Author(s):  
David A. Okaya ◽  
Eleni Karageorgi ◽  
Thomas V. McEvilly ◽  
Peter E. Malin
Keyword(s):  
Dominant Frequency ◽  
Two Dimensional ◽  
Spectral Filtering ◽  
Linear Rate ◽  
First Order ◽  
Fourier Frequency ◽  
Time Space ◽  
Extended Range ◽  
Energy Application ◽  
The Relationship

Vibrator‐to‐ground coupling can produce resonance‐induced energy that propagates with the primary sweep and produces serious artifacts in the correlated seismogram due to the frequency structure of this offending energy. For sweeps linearly increasing in frequency, the resulting artifact is observed (uncorrelated) to increase in frequency at a linear rate differing from the original sweep. Upon crosscorrelation with the pilot sweep, the artifact‐producing energy becomes distributed over an extended range of time while the normal reflected sweep is compressed, by design, into a narrow correlation wavelet. The resulting traces thus exhibit strong amplitudes that increase monotonically in dominant frequency. Display of individual uncorrelated seismograms using a Fourier frequency‐uncorrelated time (F-T) transformation reveals the relationship between the primary sweep and the induced artifact. “Surgical” filtering in this new F-T space provides for a first‐order removal of both the artifact and the energy in sweep harmonics as induced by the stong first arrivals. Two‐dimensional (2-D) spectral filtering of the modulus of the (complex) 2-D transform of the F-T data provides better rejection of the unwanted energy. Application of this trace‐by‐trace filtering process to a badly contaminated crustal-scale multichannel CDP profile in the southern San Joaquin Valley, California, reveals significant reflections from the middle and lower crust that were obscured in the unfiltered profile.

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